On 2/1/2013 10:21 AM, Mark Bayern wrote:
Someone brought out the fact that a power strip or some other device with a surge protector built in should cover everything on that particular leg. It's a parallel circuit.
Nope. ANY shunt mode device (MOV) operates by conducting the spike to the green wire or the neutral. The resulting current raises the voltage on the green wire (which is connected to the chassis of the equipment plugged into the "protected" outlet) to some very high value, depending on the spike that sets it off. In the case of lightning, this can be a lot.
Now, consider equipment connected to two different power strips, with or without an MOV, or to different locations, or to another ground. ALL of those other points will be at a different potential as a result of seeing the same spike, and again, in the case of lightning, that can be a VERY large difference. it is the DIFFERENCE in potential from one piece of gear to the other that fries those Ethernet ports, and it would also fry signal interconnect circuitry for audio and video.
THIS is why MOVs are a really bad idea on branch circuits. Those of us working in pro audio have LOTS of interconnected equipment, often at widely separated points, so we learned all of this the hard way nearly 20 years ago. Our solution has been to use SERIES-MODE Surge Protectors, and that has been quite effective. SurgeX and Brick Wall are the only two companies I know of that have licensed the series mode patent. Their products are not cheap, but they work. I have SurgeX protectors on all of my ham gear, computers, and audio/video gear.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
